This is the presentation I gave during a group interview for my position as a Fab Lab Facilitator at the Museum of Science and Industry in Chicago

1. How Matter Is Made
Fun With Protons
and Neutrons
Martin Lindsey

2. Matter that we can see, touch and smell is composed of molecules.
Molecules are composed of atoms which are made of protons, neutrons
and electrons.
So what are protons and neutrons made of?

3. Neutrons and protons are both made up of smaller particles
known as quarks.
NEUTRON
NEUTRON The neutron consists of two down quarks with charge − ⁄ 3e,
1
and one up quark with charge + ⁄ 3e. The decay of one of the
2
down quarks into a lighter up quark can be achieved by the
emission of a W boson.
This involves the “weak interaction”, a short range force
which acts on electrons, neutrinos and quarks. It is governed
or mediated by the W and Z bosons.

4. NEUTRON
NEUTRON This is called beta decay. By this means the neutron decays into a
proton(which contains one down and two up quarks), an electron, and an
electron neutrino.
Under the Standard Model of particle physics, because the neutron consists of
three quarks, the only possible decay mode without a change of baryon
number is for one of the quarks to change flavor via the weak interaction.

5. However, protons are known to transform into neutrons through the process of electron capture
(also called inverse beta decay). For free protons,
this process does not occur spontaneously but only
PROTON
PROTON when energy is supplied. The equation is:
p+ + e- → n + ν e
Remember from the neutron example that the process is reversible; neutrons can convert back to
protons through beta decay, a common form of
radioactive decay.
This occurs when the proton and neutron are part of a larger nucleus.

6. The “strong interaction” is the force through which quarks
PROTON
PROTON interact to form neutrons and protons. It also holds neutrons
and protons together to form nuclei. The gluon mediates the
strong interaction.